Battery life has always been important for laptop users. In recent years it has become increasingly important as devices like the iPad have set even higher expectations for battery life. Laptops have been trying to catch up and have been steadily improving. Ultrabooks like the MacBook Air trade features and performance for size while also maintaining solid battery life. Intel’s new Haswell CPU architecture is particularly focused on battery life, allowing Apple’s 2013 MacBook Airs to last for an amazing 12 hours, even longer than an iPad. Not content with hardware improvements alone Apple is enabling better battery life through software as well, improving run time for both new and old devices alike.
Several features of Apple’s recently announced Mac OS 10.9 Mavericks center around increasing battery life. By changing the way that applications utilize system resources and power-optimizing common tasks like video playback and web browsing Mavericks can provide a significant boost to even an older machine. My 2008 Unibody MacBook Pro with a third party SSD barely got 2 hours on a charge even with light web browsing under Mountain Lion. Part of the reason that I replaced the hard drive with an SSD (besides speed) was to see if I could squeeze a bit more time out of it. Often times a half hour of light to moderate web browsing left my battery at a 65% charge. Under the second developer beta of Mavericks I can easily get 3 hours total and still have about 80% charge after a half an hour. That’s a huge improvement for a 5 year old computer!
There are several ways that Mavericks squeezes more life out of a charge. First, it uses what is called Timer Coalescing which basically synchronizes the intervals at which applications get CPU time. The CPU is accessed by different applications thousands of times per second. In between each of those accesses is idle time where the CPU’s power consumption drops. By synchronizing multiple apps so that they all use the CPU in a block, Apple can increase idle time and lower consumption. The second way Mavericks increases battery life is called App Nap. Whenever an application is not being actively used (i.e. all of its windows are minimized or hidden behind other windows), Mavericks slows the app down by reducing the frequency at which it can access the CPU and other parts of the system. This prevents forgotten apps from sucking up power. Often times people forget to quit apps that they are no longer using and they do nothing but waste energy.
A third way that Mavericks increases battery life is by optimizing certain applications and functions. For instance, Safari now includes a “Power Saver” feature that pauses media on inactive tabs and prevents Flash elements (which are rather power inefficient) from playing until you click on them. iTunes has also been tweaked to use less power when playing back HD movies (possibly by using some of the video decoding features built into recent CPUs). The entire OS is even more energy-focused. Clicking on the battery menu now shows you which apps are using “significant energy” so you can shut them down. The Activity Monitor even includes an Energy tab that tells you the “energy impact” of each application so that you can take more control of your battery life. Apple has a great explanation of each of these features on the Advanced Technologies page of its Mavericks preview.
So far all of these changes have really made a difference to me. I generally use my MacBook to surf the web and listen to music and I have noticed significantly increased battery life without any performance penalty. I’m not sure how much of a difference it would make if I was downloading files in the background, compiling software, or organizing and editing photos, but for moderate web browsing I definitely see a difference. At the moment not everyone using the beta is seeing the same improvements I am but they probably have heavier workloads and newer hardware that is already more energy efficient than mine. I’ll be very interested to see how Mavericks would affect the already fantastic battery life of the new MacBook Air and if my battery life will get even better as third party applications start optimizing for energy efficiency. At the moment I’m extremely impressed and would recommend Mavericks to anyone for battery improvements alone.